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Energy Changes in molecules and atoms (CH2105)

Aims

This module aims to teach the principles and laws of thermodynamics, the concepts of phase diagrams, and the principles of electrochemistry and their relationship to thermodynamics.

General description

This module will introduce the basic ideas of thermodynamics. Enthalpy, Entropy and Free Energy will be discussed with reference to equilibria of reactions. The concept of the chemical potential will be introduced with reference to phase stability, condensation processes and the properties and applications of supercritical fluids.

The module will also include the link between electrode potentials and free energies of reaction.

Syllabus content

Basic concepts: definitions, state functions and non-state functions - work, heat energy etc.

First law of thermodynamics and conservation of energy. Reversible and non-reversible changes.

Relationship between heat and enthalpy, enthalpy measurements (bomb calorimeter). Enthalpy changes (fusion, sublimation, ionisation, dissociation), Hess’s law, enthalpy of formation (Born-Haber Cycles).

Second law of thermodynamics: Entropy (definitions and entropy change). Statistical and macroscopic interpretation of entropy changes (brief overview). Phase transitions and the chemical potential (brief introduction) and relevance to phase stability, condensation processes and the properties and applications of supercritical fluids.

Standard molar Gibbs free energy and relationship to equilibrium constant. Properties of Gibbs functions including pressure and temperature dependence.

Phase diagrams and the phase rule. 1 and 2 component systems. Multicomponent systems and Van’t Hoff equation.

Development of an interfacial potential difference at metal liquid and membrane interfaces. Electrochemical potentials, common electrodes - metal / metal ion. Reference potentials and standard electrode potentials.

Practical work :

Experiments to practice the measurement and recording of reaction enthalpies and entropies using thermodynamic cycles and the Van’t Hoff equation. Phase transitions and the effect of temperature. Measurement of electrochemical potentials and determining free energies from electrochemical cells.